1. Field of the Invention
The present invention relates to a method of simultaneously and quickly forming (boring) orifices as ejection nozzles (hereinafter called xe2x80x9corificesxe2x80x9d) with the accurate shape in the orifice plate of an ink-jet printer head.
2. Description of the Related Art
Recently, ink-jet printers are widely used. The ink-jet printers include a thermal jet type which ejects ink droplets under the pressure of bubbles that are generated by heating the ink by means of a heat-generating resistor element and a piezoelectric type which ejects ink droplets by pressure that is applied to the ink by the deformation of a piezoelectric resistor element (piezoelectric element).
Because those types of printers do not require a developing step and transfer step and directly eject ink droplets on a recording medium to record information, they are advantageous over an electrophotographic type which uses powder-like toners in easy miniaturization and lower printing energy. The ink-jet printers are therefore popular particularly as personal printers.
The thermal jet type printer heads are classified into two structures depending on the ejection direction of ink droplets. The first type is a side-shooter type thermal ink-jet printer head which ejects ink droplets in a direction parallel to the heat generating surface of the heat-generating resistor element. The second one is a roof-shooter type or top-shooter type thermal ink-jet printer head which ejects ink droplets in a direction perpendicular to the heat generating surface of the heat-generating resistor element. The roof-shooter type thermal ink-jet printer head, in particular, is known for its very low power consumption.
FIG. 1A is a perspective view showing the structure of a printer equipped with such a roof-shooter type thermal ink-jet printer head, FIG. 1B is a plan view showing the ink ejecting side of the ink-jet printer head, FIG. 1C is a cross-sectional view from the direction of C-Cxe2x80x2 in FIG. 1B and FIG. 1D is a plan view exemplarily illustrating a silicon wafer from which this ink-jet printer head is manufactured
A printer 1 shown in FIG. 1A is a compact printer for home and personal usage, and has a carriage 2 to which an ink-jet printer head 3 that prints and an ink cartridge 4 that retains ink are attached. The carriage 2 is supported slidable by a guide rail 5 and is also secured to a serrated drive belt 6. With this structure, the ink-jet printer head 3 and the ink cartridge 4 are reciprocally moved in the main print scanning direction indicated by a double-headed arrow B in the diagram. This ink-jet printer head 3 is connected to an unillustrated control unit in the main body of the printer 1 by a flexible communication cable 7. The control unit sends print data and control signals to the ink-jet printer head 3 via the flexible communication cable 7.
Located at the lower end portion of a frame 8 is a platen 9 which faces the ink-jet printer head 3 and extends in the main scanning direction of this head 3. Paper 10 is intermittently fed, in contact with the platen 9, in a printing sub-scanning direction indicated by an arrow C in the diagram by paper feed rollers 11 and paper discharge rollers 12. During the stationary period in the intermittent feeding of the paper 10, the ink-jet printer head 3 ejects ink droplets on the paper 10 in close proximity and prints on the paper 10 while being driven by a motor 13 via the serrated drive belt 6 and the carriage 2. Printing on the paper 10 is accomplished by repeating the intermittent feeding of the paper 10 and the ink ejection during the reciprocal movement of the ink-jet printer head 3.
While, as such a printer, monochromatic printers were the man stream in the past, full-color printers have recently become rather popular. The ink-jet printer head 3 for use in a fill-color printer has four parallel orifice columns 16 for ejecting four respective color inks formed on an orifice plate 15 which is laminated on a chip substrate 14 with a size of, for example, 10 mmxc3x9715 mm, as shown in FIG. 1B. Each orifice column 16 has 128 orifices 17 formed in a line for a resolution of 360 dpi, for example, or has 256 orifices 17 for a resolution of 720 dpi.
One way of manufacturing such an ink-jet printer head is to simultaneously form multiple orifices, a plurality of heat generating elements, and drivers which respectively drive those elements in a monolithic form by utilizing silicon LSI technology and thin film technology. According to this method, heat generating elements 18 and drivers 19 respectively associated with the 128 or 256 orifices 17 are formed on the same chip substrate 14.
Multiple ink-jet printer heads 3 are simultaneously formed on a silicon wafer 21 as shown in FIG. 1D. Formed on each of a predetermined number of chip substrates 14 are individual wiring electrodes 22 for driving the respective heat generating elements 18 and a common electrode 23, wiring leads 24 and power supply leads 25 connected to those electrodes, a partition 27 for forming ink flow passages 26, an ink feed hole 28 for receiving ink to be supplied from the external ink cartridge 4 to the ink flow passages 26 and a common ink feed groove 29 in addition to the orifices 17, the heat generating elements 18 and the drivers 19.
The ink-jet printer heads 3 whose individual components are formed in this manner on the silicon wafer 21 are finally cut out into individual units along scribe lines using a dicing saw or the like. Each separated unit is die-spotted to a mount substrate with its leads connected to those of the substrate, thereby completing the ink-jet printer head 3.
At the time of printing, the heat generating elements 18 in the ink-jet printer head 3 are selectively energized or activated in accordance with print information, spontaneously generating heat to cause a film boiling phenomenon on the inks. As a result, ink droplets are ejected from the orifices 17 corresponding to the heat generating elements 18 that have generated heat. According to this ink-jet printer head 3, the ink droplets are ejected in an approximately spherical shape corresponding in size to the diameter of the orifices 17 and are printed in about double the size on paper.
Conventionally, the orifices 17 are bored in the orifice plate 15 on each chip substrate 14 by using an excimer laser technique or wet or dry etching. According to the dry etching scheme, after a metal film of Al, Ni or Cu is laminated on the orifice plate 15, it is patterned and the orifice plate 15 is selectively etched by an ordinary dry etching system with the patterned metal film used as a mask.
In the step of boring the orifices, it is demanded to accurately form, for example, 128 orifices 17 of a predetermined size and shape at predetermined locations. The conventional method however has a difficulty in simultaneously and accurately forming the multiple orifices 17 of a predetermined size and shape in the thick orifice plate 15 at predetermined locations. Conventionally, therefore, orifices are formed an adequate quantity at a time, in the orifice plate, so that boring the whole orifices takes time.
Accordingly, it is an object of the present invention to provide a method of manufacturing an ink-jet printer head, which can simultaneously and accurately form multiple orifices as ejection nozzles at predetermined locations and in a predetermined size and shape in a short period of time.
To achieve this object, according to one aspect of this invention, there is provided a method of manufacturing an ink-jet printer head having a substrate provided with a plurality of energy generating elements for generating pressure energy for ejecting inks and an orifice plate located on the substrate and having a plurality of ejection nozzles formed therein for ejecting inks in a predetermined direction by pressure generated by the energy generating elements, the method comprising the steps of forming an etching mask film having a pattern corresponding to the ejection nozzles in the orifice plate before forming the ejection nozzles; and forming the plurality of ejection nozzles in the orifice plate by dry etching with helicon wave plasma source (hereinafter referred to as xe2x80x9chelicon-wave dry etchingxe2x80x9d) while cooling a printer head substrate having the orifice plate with the mask film placed on the substrate.
According to this method, as ejection nozzles are bored while cooling the printer head substrate which is to be etched using helicon-wave dry etching that can ensure fast etching with a large ion current, it is possible to reliably prevent the temperature of the printer head substrate undergoing a treatment from excessively rising which would otherwise adversely affect the shape of the ejection nozzles to be bored. This can permit multiple ejection nozzles of the desired and adequate size and shape to be simultaneously and quickly bored.
It is preferable that in this method, the orifice plate is a multilayer sheet having a thermoplastic adhesive layer having a glass transition point higher than 200xc2x0 C. deposited on each side of a polyimide sheet. In this case, the printer head substrate may be cooled to 200xc2x0 C. or lower. This overcomes the conventional problem that the thermoplastic adhesive layers are thermally over-expanded to thereby adversely affect the forming of the ejection nozzles.
In the above method, it is preferable that the printer head substrate is cooled by cooling a bottom of the substrate with a coolant gas. In this case, when the ejection nozzles are bored through, the coolant gas is blown out of the ejection nozzles. The first adequate scheme of preventing this shortcoming is such that after an ink feed passage penetrating from the bottom of the substrate to a top surface thereof is formed, the ink feed passage is blocked before supply of the coolant gas starts, and after forming of the ejection nozzles is completed and supply of the coolant gas is stopped, blocking of the ink feed passage is released. In this case, the ink feed passage has only to be blocked by adhering a block sheet on the bottom of the substrate, and the blocking of the ink feed passage has only to be released by removing the block sheet.
The second adequate scheme of preventing the above shortcoming is such that before supply of the coolant gas starts, a plurality of ink leading passages extending from an ink feed passage penetrating from the bottom of the substrate to a top surface thereof to the energy generating elements provided on the top surface of the substrate are blocked, and after forming of the ejection nozzles is completed and supply of the coolant gas is stopped, blocking of the ink leading passages is released. In this case, the ink leading passages has only to be blocked by filling a dissolvable resin easily dissolvable by a solvent and the blocking of the ink leading passages has only to be released by dissolving the dissolvable resin.
It is preferable that the dissolvable resin is filled in such a way as to cover the energy generating elements. This prevents the energy generating elements from being damaged by over-etching.
The third adequate scheme of preventing the above shortcoming is such that the ejection nozzles are bored before an ink feed passage penetrating from the bottom of the substrate to a top surface thereof is opened. In this case, the ink feed passage has only to be formed by connecting an ink feed groove on a top surface side of the substrate to an ink feed hole on a bottom side of the substrate and one of the ink feed groove and the ink feed hole needs only to be formed to open the ink feed passage after forming of the ejection nozzles. It is more preferable that the ink feed hole is formed to open the ink feed passage after forming of the ejection nozzles.
The fourth adequate scheme of preventing the above shortcoming is such that after supply of the coolant gas to the bottom of the substrate of the printer head substrate starts, the helicon-wave dry etching is initiated and the supply of the coolant gas is stopped immediately after substantially all of the ejection nozzles are bored through. In this case, it is preferable that the timing at which substantially all of the ejection nozzles are bored through is detected from a change in a flow rate of the coolant gas.
To achieve the above object, according to another aspect of this invention, there is provided a method of manufacturing an ink-jet printer head for performing recording by applying pressure energy to ink and ejecting the ink onto a recording medium from a plurality of ejection nozzles, comprising the steps of arranging a plurality of energy generating elements for generating the pressure energy on a substrate; placing, as an orifice plate, a thin film sheet having adhesive layers adhered to both of top and bottom sides thereof on the substrate with the energy generating elements arranged thereon; and simultaneously boring a plurality of ejection nozzles in the orifice plate in association with the energy generating elements by dry etching while cooling a printer head substrate having the orifice plate placed on the substrate with a coolant gas applied to a back side of the substrate.
According to this method, even if a thin film sheet having thermoplastic adhesive layers adhered to both sides thereof, which is excellent in working efficiency, is used as an orifice plate, a rise in the overall temperature of the printer head substrate during dry etching is suppressed. This can prevent the thermoplastic adhesive layers from being thermally over-expanded, which would otherwise adversely affect the forming of the ejection nozzles and can permit multiple ejection nozzles of the desired and adequate size and shape to be simultaneously and quickly bored. It is therefore possible to provide a method of manufacturing an ink-jet printer head equipped with ejection nozzles of the desired and adequate size and shape at a high working efficiency.
According to the second method, if helicon-wave dry etching is used as dry etching, multiple ejection nozzles of the adequate shape can be bored faster. This further improves the throughput of the manufacture of ink-jet printer heads.